Device for use in manufacturing electrotypes



Nov. 1, 1955 H. L. BISHOP 3 3 DEVICE FOR USE IN MANUFACTURINGELECTROTYPES Filed Aug. 10, 1954 IN V EN TOR.

HIS ATTORNEYS United States Patent 'OfiFice 2,722,261 v fatented Nov.1,1955

DEVICE FOR USE IN MANUFACTURING ELECTROTYPES Homer L. Bishop, Dayton,Ohio, assignor of thirty per cent to Earl E. Stansell, West Carrollton,Ohio Application August 10, 1954, Serial No. 448,910

' 6' Claims. (Cl. 153-32 This invention relates to a device for use inmanufacturing electrotype plates and more particularly to a device formaintaining a high degree of accuracy in the size of electrotype platesduring the curving process.

When the electrotype plate is subjected to the curving process,distortion of the impression on the plate is inevitable, due to stressesset up within the shell and backing metal when the curving takes place.curving process, unless some means is used to prevent, actual stretchingof the shell occurs on its surface, and distortions occur due topressures set up within the backing metal. The fidelity of theimpression is thus ruined.

The importance of maintaining uniformity in the size of a series ofshells is particularly important in color printing where perfectcoincidence of images is necessary to prevent overlapping.

The object of the present invention is the provision of a device orcurving frame for maintaining the shell exactly at its original length,and further to provide for even curving of the backing metal so that nobuckling occurs from pressures which are set up within it, and nodistortions of the image on the shell occur from this cause.

A further object of the invention is the provision of means forpreventing stress in the backing metal, and means for preventing thelengthening of cracks once they are formed.

A further object of the invention is the provision of a device forholding a shell and backing during the process of curving, and onewherein the shell and backing are maintained at a set of predetermineddimensions during the curving process. This includes the length of boththe inside and outside circumferences.

A further object of the invention is the provision of a device for usein the curving process of electrotype plates which provides forcorrection of inaccuracies in the size of the electrotype plates, sothat accurate dimensions and an accurate curvature are obtained in thefinished product.

Other objects and advantages reside in the construction of parts, thecombination thereof and the mode of operation, as will become moreapparent from the following description.

In the drawing,

Figure 1 is a perspective view of an electrotype plate comprising ashell and backing, held within the device of the invention.

Figure 2 is a schematic view showing a shell and backing of anelectrotype plate secured in the device of the invention, and beingpassed through curving rollers.

Figure 3 is a cross sectional view of the device of the invention afterit has been subjected to the curving process.

Figure 4 is a schematic view of the electrotype plate after the curvingprocess.

Referring more in detail to the drawing, a form or curving frame,generally indicated by the numeral 10, consists of a pair of steelretaining bars 12, a bendable steel plate 14, a metal having hightensile strength, and an elastomeric enclosing member 16.

The steel bars 12 are shown as riveted at 18 to the steel plate 14; butthe attachment can be made in any desired manner.

As will be noted in the drawing, the bars 12 are quadrilateral in crosssection; the inward or facing edges are formed at an angle to thenormal. This angular shape of the bars functions as a holddown engagingbeveled margins of the electrotype shell so as to prevent the ends fromcurving away from the plate 14. In the present instance, and for presentuses, this angle is 12 from the normal, making the angle between theplate 14 and the slanted edge 20 an exact angle of 78. However, theinvention is not limited to this specific angle in that the angle'may beincreased or decreased within certain limits.

The enclosing member 16 is made of rubber, or other elastomer, andreceives the form 10, enclosing it on all In the usual sides with theexception of the upper surface of the bars 12 and the space betweenthem.

The electrotype 22, consisting of the shell 24 and backing metal 26, ofsoft metal, such as lead, as is common in the art, is placed in thisspace by sliding it in from an edge portion. The ends of the shell andbacking are beveled at an angle to coincide as nearly as possible withthe 78 angle between the plate and the retaining bars. If there areinaccuracies in this operation, and the abutting ends do not accuratelycoincide, this inaccuracy is cared for and corrected during the curvingprocess.

During the curving process the shell lies flatly against the surface ofthe steel plate, and its ends fit accurately to the inward surfaces ofthe bars 12. The shell is thus protected against anystretching or otherchange in size,

and the image it carries on its surface remains completely and perfectlyintact, and free from any sort of distortion.

The form 10, carrying the electrotype plate is passed between suitablyarranged curving rollers. Figure 2 shows an inner roll 28 and a pairofouter rolls 30. The present invention is not limited to any specificnumber or any specific arrangement of rollers, or, in fact, to anyspecific curving process. The important thing is that the exactness ofthe impression upon the shell remains intact in any curving process thatis desired to be used.

In Figure 3 is shown the form and the electrotype plate after they haveemerged from the curving rollers. The outward ends of the form are nowsprung downwardly, and the finished electrotype plate is released.

When the curving is finished and the electrotype plate, together withthe steel plate 14 and the enclosing elastomer 16 have emerged from therollers, the plate 14 and the curving frame are held in curved positiondue to the fact that the inclined margin 20 of the bar 12 is held by thebeveled margins of the curved electrotype plate 14. By merely deflectingone end of the curving frame so as to place a reverse curve in theportion of the curving frame adjacent the bar 12, this bar then clearsthe end of the electrotype plate. As soon as this takes place, thecurving frame shapes into a straight position, ejecting the electrotypeplate.

When using multi-color electrotype plates, it is very important that allof the electrotypes register. During the process of casting the backingmetal on the shell, the shell may be distorted due to stresses set up,caused by temperature changes and shrinkage when the backing metalsolidifies and cools. That being the case, even though all of the shellsof a set of electrotype plates used in multi-color printing may beidentical in dimensions before application of the backing metal, theresulting electrotype plates may not be uniform in length. If, forexample, one electrotype plate is shorter than another of the same set,the longer one may be trimmed to size to fit between the retaining barsand the shorter one cut short. Due to the fact that the backing metal isplaced in compression during the curving of the electrotype plate, theshell will stretch, so that the length of the shell, even though &short, will stretch sufficiently so as to be equal in'length to theQthcr :electrotypeplate which was origina1ly longer. -By -the apparatusdisclosed herein, ;it is therefore possible to compensate forirregularities resulting from, the casing of the backing metal.

,In curving an electrotype, the backing metal ,is compressed. ,In theelectrotype shownherein, a plurality of substantially conical holes 40,arranged in rows and tiers in the-back side of the backing metal,provide pockets into ,which some of the surplus metalcaused by thecurving operation mayfiow, thereby-reducing the diameter of theholes.furthermore,these holes limit-the cracking of the,eleotrotype plates andthereby prolong the lifeof the electrotype plates. If a crack develops,it will developin the weakest areas. This, of course, would be betweentwo adjacent holes. However, when a crack does develop between two.adjacent holes, the .holes will limit the length of the crack, so thatthe crack will not-extend across a large area of the electrotype plate,resulting in failure. This has been more fully describedin my copendingapplication Serial No. 448,911, filed Aug. 10, 1954, for Device for Usein Manufacturing Electrotype Plates.

Due to the fact that the electrotype plate is substantially equal ,inthickness to the thickness of the steel plate 14 and the elastomer orenclosing member 16, it can readily be seen that the face of theelectrotype plate lies in a neutral plane ,where, if it were bonded tothe steel plate 14, it would receive the maximum shearing stresses,assuming the materials to be homogeneous throughout.

Although the preferred embodiment of the device has beendescribed, itwill be understood that within the purview of this invention variouschanges may be made in the form, details, proportion and arrangement ofparts, the combination thereof and mode of operation, which generallystated consist in a device capable of carrying out the objects setforth, as disclosed and defined in the appended claims.

Having thus described my invention, I claim:

1. A device for use in the manufacture of electrotype platescomprising abendable steel plate, a pair of metal retaining bars positioned inparallelism and secured to said plate, the inward facing edges of saidsteel bars being so inclined as toform an angle of 78 with said bendableplate, anelastomeric form partially encompassing saidsteel plate andsaid parallel bars, said parallel bars forming avspace for confining theshelland backing of an electrotype plate.

2. A device for use in the proces of curving electrotype plates, whichcomprises a bendable steel plate, a pair of steel bars placed inparallel position and secured to said plate, the inner facing edges ofsaid bars forming an acute with said bendable late, said bars forming aspace for holding the shell and backingmetal of an electrotype plate,

3. A device for use in the process of manufacturing curved electrotypeplates having beveled margins including a shell and backing metal, saiddevice comprising a bendable steel plate for flatly supporting saidshell, a pair of retaining bars secured to said plate, and placed inparallelism, the inward facing walls of said bars being formed at anangle to the normal so as to snugly .fit the beveled margins of the,electrotype plates, an elastomeric enclosing member covering all areasof said steel plate lying outside the space occupied by said electrotypeplate.

4. A device for use in the process of manufacturing curved electrotypeplates having an, impression .carrying shell provided with backingtmetal.on the rear surface ,of theshell, the ends.of the plate'beingbevelled,saidtdevice including a sheet of metal that is bendable and that hashigh resistance to elongation .as compared with the backing metal, apair Lof plate retaining bars extending across said sheet of metaladjacent the .ends thereof and .fixedly secured ithereto, said barsextendingparallelto each other, the tinwardly facing edges of the barsbeing formed at an acuteangle with respect .to the adjacent portions ofthe shell-.0f-metal, so thatas thebevelled ends of the plate arepositioned against the inclined facing edges of the bars, these holdtheplate against the sheet of metal.

5. A device accordingto claim 4 wherein the side of the sheet of,met-alopopsitethebars iscovered with an elastomeric material permanentlysecured to the metal, the combined thickness of the sheetof metal andthe elastomeric :material being substantially equal to the thicknessof-the plate.

6 A device according toclaim4 wherein an elastomeric member.encloses:the sheet of metalon all sides excepting the upper surface of:the :bars and the space between the bars.

References Cited in the file of this patent UNITED STATES PATENTS395,488 Dale Jan. 1, 1889 1,173,363 McCarroll Feb. 29, 1916 FOREIGNPATENTS 169,486 ,Germany Apr. 5, 1906

